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[fpgaboy.git] / diag.asm

diff --git a/diag.asm b/diag.asm
index 5d44cef29f6ba6c9654ef0dada74bf8868e4ae68..50cefe73b0dff3747ce10de9d9d98202859e9b01 100644 (file)
--- a/diag.asm
+++ b/diag.asm
@@ -52,12 +52,7 @@ signon:
 
 putscreen:
        ; Wait for vblank
-       ld c, $41
-.stat: ld a, [c]
-       ld [$FF51], a
-       and $03         ; mode
-       cp $01          ; VBLANK
-       jr nz, .stat
+       call .vblwait
 
        ld hl, $8000    ; Copy two tiles.
        ld a, $AA
@@ -103,13 +98,30 @@ putscreen:
        ld [hli], a
        
        ld hl, $9800
+.vloop:        call .vblwait
+       ld c, $40
 .loop: ld a, $01
        ld [hli], a
        xor a
        ld [hli], a
        ld a, h
        cp $9C
-       jp nz,.loop
+       ret z
+       dec c
+       xor a
+       cp c
+       jr nz,.loop
+       jr .vloop
+
+.vblwait:
+.stat1:        ld a, [$FF41]   ; STAT
+       and $03
+       cp $00
+       jp nz, .stat1
+.stat2:        ld a, [$FF41]
+       and $03
+       cp $01
+       jr nz, .stat2
        ret
 
 vbl:
@@ -121,16 +133,34 @@ vbl:
        xor a
        ld [$FF0F], a
 
-       ld c, $42       ; SCY
-       ld a, [c]
-       inc a
-       ld [c], a
+       ld a, [$FF51]
+       ld b, a
+       and $80
+       cp $80
+       jr nz, .nothing
+       ld c, $0
+
+       ld a, b
+       and $1
+       cp c
+       call nz, .scyup
        
-       ld c, $43       ; SCX
-       ld a, [c]
-       inc a
-       ld [c], a
+       ld a, b
+       and $2
+       cp c
+       call nz, .scydown
+       
+       ld a, b
+       and $4
+       cp c
+       call nz, .scxup
+       
+       ld a, b
+       and $8
+       cp c
+       call nz, .scxdown
 
+.nothing:
        POP HL
        POP DE
        POP BC
@@ -138,6 +168,23 @@ vbl:
 
        RETI
 
+.scyup:        ld hl, $FF42
+       inc [hl]
+       ret
+
+.scydown:      ld hl, $FF42
+       dec [hl]
+       ret
+
+.scxup:        ld hl, $FF43
+       inc [hl]
+       ret
+
+.scxdown:      ld hl, $FF43
+       dec [hl]
+       ret     
+       
+
 lcdc:
        PUSH AF
        PUSH BC